Fish, The Nen'e Cell as a Unit. 103 



line ; and a loss or condensation of the open reticulated appear- 

 ance. The control ganglion showed none of these changes. 

 If, after stimulation, the cells were permitted to rest and then 

 examined, these changes were not apparent. For the study of 

 normal fatigue, certain birds and bees were examined, some 

 of them were killed before entering their daily routine, while 

 their cells were presumably as yet in a state of rest ; others 

 were killed just at night-fall after the completion of their day's 

 work. A comparison of those killed in the morning with 

 those killed in the evening, showed in the latter changes as 

 marked as those produced by artificial fatigue. To make the 

 evidence still stronger, and to show that the effects were not 

 the result of histological reagents, it remained for Dr. Hodge 

 to study the living cell. For this purpose he chose the cells 

 of the sympathetic ganglia of the frog. Two frogs were pre- 

 pared in exactly the same way, except that one received a weak 

 electrical stimulation while the other did not. The unstimu- 

 lated frog showed no change, while the nucleus of the cells of 

 the stimulated frog showed very marked shrinkage and irregu- 

 larity of outline. Certain well defined changes in the constitu- 

 tion of the nerve cells of very old persons as compared with the 

 newly born have also been demonstrated. Hodge has shown 

 that fatigue effects occur in brain cells as well as those of the 

 spinal ganglia. 



As early as 1884, Flesch noted differences in cells in their 

 reaction to staining reagents due to internal modifications as an 

 effect of their functional activity, and according to this affinity 

 for color he designated the cells as chromophile and chromo- 

 phobe. 



Vas ('92 ) has demonstrated changes in the cells of the cer- 

 vical ganglia, due to their functional activity, and confirms, in 

 the main, the points that have just been stated. As a prelim- 

 inary result of this activity Vas has further noted that there is, 

 at first, a swelling of the cell. This has also been confirmed by 

 Mann ('94) who has extended the observations to the motor 

 cells of the spinal cord and the sensory cells of the retina of the 

 dog. From his researches, Mann concludes that during rest, 



